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Recovery after Oracle mistakenly deletes table dataTest environment:SYSTEM:IBM AIX 5L Oracle version:10gr2 1. Query and modification of undo_retention parameters Use the show parameter Undo command to view the current database parameter

PersonAreIn useSQLHourOften fall intoIncorrectArea, that is, tooOffNote on the obtainedEndIf they are correct, they are ignored.ImplementationMethodRoomPossible performance differences,ThisPerformance differences between large orComplexDataLibrary

Many people tend to fall into a misunderstanding when using SQL, that is, they are too concerned about whether the obtained results are correct, while ignoring the possible performance differences between different implementation methods, this

This article from: http://bbs3.chinaunix.net/viewthread.php? Tid = 83481 Author: Honorary moderator-genie enabling 1. Rational Use of Indexes An index is an important data structure in a database. Its fundamental goal is to improve query efficiency.

Clustered index,The data stored in the table is stored in the order of indexes. the retrieval efficiency is higher than that of normal indexes, but it has a greater impact on the addition, modification, and deletion of data. Non-clustered IndexDoes

---- People tend to fall into a misunderstanding when using SQL, that is, they are too concerned about whether the obtained results are correct and ignorePerformance differences may exist between different implementation methods. This performance

I. unreasonable index design ---- For example, a table with 620000 rows of record and rows with different indexes has the following SQL statements: ---- 1. A non-cluster index is created on date. Select count (*) from record where date> '20140901'

Clustered index,The data stored in the table is stored in the order of indexes. the retrieval efficiency is higher than that of normal indexes, but it has a greater impact on the addition, modification, and deletion of data. Non-clustered

I. unreasonable index design ---- For example, a table with 620000 rows of record and rows with different indexes has the following SQL statements: ---- 1. A non-cluster index is created on date. Select count (*) from record where date> '20140901'

Today, we tested the restoration method for Oracle after deleting table data. There is a table in the maintenance test of the Oracle production system. The data in the table is deleted and commit. The service cannot be interrupted (the database

----people in the use of SQL often fall into a misunderstanding, that is too focused on the results are correct, and ignore the different implementation methods may exist between Performance variance, which is particularly evident in large or

First, unreasonable index design ----Example: The table record has 620000 rows, and the following SQL runs under different indexes: ----1. A non-clustered index was built on date Select COUNT (*) from the record where date > ' 19991201 ' and date 20

oracle| optimization 1. The statements that have been validated are exactly the same as those already in the shared pool 2. Variable names as consistent as possible 3. Rational use of outer joins 4. Use fewer layers of nesting 5. Multi-use

----people often get into an error when using SQL, that is too focused on the results are correct, but ignores the different implementation methods may exist between the performance difference, This performance difference is particularly evident in

People tend to get into a misunderstanding when they use SQL, it is too focused on whether the resulting results are correct, ignoring the possible performance differences between different implementations, which are particularly evident in large or

We know that stored procedures do not support unfixed parameters (including array parameters), but sometimes our parameters must be unfixed. What should we do? We know that stored procedures do not support unfixed parameters (including array

Amxking Determine whether there are any injection points; And 1 = 1 and 1 = 22. Generally, the name of a table is admin adminuser user pass.Password ..And 0 (select count (*) from *)And 0 (selectCount (*) from admin) --- determine whether the admin

Oracle 12C TRUNCATE TABLE CASCADE The truncate table cascade statement is provided in Oracle 12c to delete the association when the TABLE has a primary foreign key relationship and is cleared. The following is a demonstration. 1. Prepare the test

SQL exists, in, sqlexistsinTips:1. When the External table is a large table and the inner table is a small table, use exist2. When the External table is a small table and the internal table is a large table, the inExample: The External table is

Delay Section Function of Oracle 11gR2 In versions earlier than 11gR2, when creating a table, the segment space is automatically allocated, which has several drawbacks: 1. space needs to be allocated during initial table creation, which naturally